Geiger-muller counter



Spt 19, 1950 M. H. sHAMosv 2,522,902

GEIGER-ML-.LER COUNTER Filed July 25, 1948 Patented Sept. 19, 1,950

UNITED STATES PATENT OFFICE `6 Claims.

This invention relates to improvements in metal Geiger-Mller counters.

Many cosmic-ray experiments require the construction of large quantities of metal Geiger- Mller counters. In fabricating such counters in the past, it has been the practice to make both ends of the central wire thereof accessible for flashing, and to insert an additional bushing for lling. Such counters are relatively expensive to manufacture, and of only fair mechanical strength and reliability.

The primary object of this invention is to provide a metal Geiger-Mller counter that is highly durable, reliable in performance, of good mechanical strength, and of low cost of manufacture.

Further objects and advantages of this invention as well as its construction, arrangement and operation will be apparent from the following description and claims in connection with the accompanying drawing, in which:

Fig. 1 is a sectional elevation of a metal Geiger- Mller counter, showing a preferred embodiment of the invention; and

Fig. 2 is a sectional elevation of a modied form thereof.

Similar numerals refer throughout the several views.

In the preferred embodiment shown in Fig. 1, cathode II is a length of copper or brass tubing that is acid-cleaned and polished on the inside with steel Wool so as to eradicate the usual die scratches. A rst end cap I3 is spun from ilat stock to fit closely over one end of the cathode I I, and is sealed thereto by soft solder I5. A hole is drilled through the center of said end cap I3 to receive the rst bushing hereinafter described. A second end cap I'I is likewise spun from dat stock to nt closely over the other end of the cathode II, and is sealed thereto by soft solder I9. A hole is drilled through the center of said end cap I'I to receive the second bushing hereinafter described.

A rst bushing 2|, made of heavy-wall, lowe'xpansion horosilicate glass tubing, known under the trade name Pyrex is provided with a first metallic band 23 deposited on said bushing intermediate the ends thereof and a second metallic band 25 deposited on said bushing at an end thereof. Bushing 2| is inserted into the hole in end cap I3, positioned co-axially with cathode I I, and secured in that position by means of a soft solder seal 2'I binding end cap I3 to metallic band 23. Thus, bushing 2| extends into the cathode, thereby forming a protective sleeve over an end of the central Wire hereinafter described.

toy similar parts (Cl. Z50-27.5)

A second bushing 29, likewise made of heavywall Pyrex tubing, is provided with a metallic band 3| deposited on said bushing intermediate the ends thereof, at which point the bushing is also provided with an interior constriction 33 adapted to seat the Spring hereinafter described. Bushing 2B is inserted into the hole in end cap I'I, positioned co-axially with cathode II, and secured in that position by means of a soft solder seal 35 binding end cap I1 to metallic band 3|. Thus, bushing 29 extends into the cathode, thereby forming a protective sleeve over an end of the central wire hereinafter described.

Central wire 3l is cut to desired length and one end is spot-welded to the apex end of conical and helical spring 39. The other end of said wire 3l is spot-welded to a short length of nickel wire 4I. The wire assembly is then threaded through the bushings with the aid of a length of drill rod, with the nickel wire protruding through a small clearance hole in the center of a grid cap 43, which is soldered to metallic band 25 while the spring 39 is held in tension against the constriction 33 of bushing 29. A drop of solder is employed to seal said wire 4I to cap 43. Electrical connecting posts comprise said grid cap 43 and a Fahnestock clip 4l soldered to cathode II.

The counter is sealed to the lling system, after washing with solvents, by means of the bushing 29, which is sealed oif after filling.

In the modified form of the device as shown in Fig. 2, cathode 49 is a length of copper or brass tubing that is acid-cleaned and polished on the inside with steel wool so as to eradicate the usual die scratches and then the ends of said cathode are spun down to a diameter substantially equal to the outside diameter of the bushings 2| and 29. The device is then assembled in the manner hereinabove described with the spun-down portions of the cathode 49 providing integral end caps in lieu of the separate end caps I3 and I'I. The elimination of such separate end caps thus permits the omission of the step of sealing end caps to the cathode tube and has proved to be an advantageous simplication in counters of comparatively small diameter.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

I claim:

1. A Geiger-Mller counter comprising a cathode, a pair of bushing tubes carried in axial alignment therewith, a plurality of metallic bands deposited on said bushings, selected bands being sealed to said cathode and a selected band being sealed to a grid cap mounted on one of said bushing tubes, a wire assembly carried by said bushings, and means to couple conductors to said grid cap and to said cathode.

2. A Geiger-Mller counter comprising a cathode, a first end cap sealed to one end of said cathode, a second end cap sealed to the other end of said cathode, a pair of bushing tubes carried by said end caps in axial alignment with said cathode, a plurality of metallic bands deposited on said bushings, selected bands being sealed to said end caps and a selected band being sealed to a grid cap mounted on one of said bushing tubes, a Wire assembly carried by said bushings, and means to couple conductors to said grid cap and to said cathode.

3. A Geiger-Mller counter comprising a tubular cathode, a rst end cap sealed to one end of said cathode, a second end cap sealed to the other end of said cathode, a rst Pyrex bushing tube,

provided with a first metallic band deposited thereon intermediate the ends of said bushing and a second metallic band deposited thereon at an end thereof, carried by said first end cap in axial alignment with said cathode with said rst end cap sealed to said first band and a grid cap sealed to said second band, a second Pyrex bushing tube, provided with a metallic band deposited thereon intermediate the ends thereof having an interior constriction intermediate the ends thereof, carried by said second end cap in axial alignment with said cathode, with said second end cap sealed to the band of said second bushing, a Wire assembly comprising a wire carrying a length of nickel wire at one end and a conical and helical spring at the other end, said assembly being secured tautly in said bushings with the base of said spring bearing against said constriction and the nickel wire secured to said grid cap, and means to couple conductors to said grid cap and to said cathode.

4. A Geiger-Mller counter comprising a tubular copper cathode, a first metal end cap softsolder sealed to one end of said cathode, a second metal end cap soft-solder sealed to the other end of said cathode, a first heavy-wall Pyrex bushing tube, provided with a first metallic band deposited thereon intermediate the ends of said bushing and a second metallic band deposited thereon at an end thereof, carried by said rst end cap in axial alignment with said cathode with said rst end cap solder-sealed to said rst band and a grid cap solder-sealed to said second band, a second heavy-Wall Pyrex bushing tube, provided With a metallic band deposited thereon intermediate the ends thereof and having an interior constriction intermediate the ends thereof, carried by said second end cap in axial alignment with said cathode, with said second end cap soft-solder sealed to the band of said second bushing, a wire assembly comprising a wire spot- Welded at one end to a length of nickel Wire and spot-welded at the other end to the apex of a conical and helical spring, said assembly being carried between said bushings with the spring thereof bearing against said constriction and the other end thereof secured to said grid cap, and means to couple conductors to said grid cap and to said cathode.

5. A Geiger-Mller counter comprising a tubular copper cathode having end portions spun down to a reduced diameter, a rst heavy-wall Pyrex bushing tube, provided with a ilrst metallic band deposited thereon intermediate the ends of said bushing and a second metallic band deposited thereon at an end thereof, carried at one end of said cathode in axial alignment therewith, said cathode being solder-sealed to said rst band and a grid cap being solder-sealed to said second band, a second heavy-Wall Pyrex bushing tube, provided with a metallic band deposited thereon intermediate the ends thereof and having an interior constriction intermediate the ends thereof, carried at the other end of said cathode in axial alignment therewith with said cathode soldersealed to the band of said second bushing, a wire assembly comprising a wire spot-welded at one end to a, length of nickel Wire and spot-Welded at the other end to the apex of a conical and helical spring, said assembly being carried between said bushings with the spring thereof bearing against said constriction and the other end thereof secured to said grid cap, and -means to couple conductors to said gridcap and to said cathode.

6. A Geiger-Mller counter comprising a cathode, a pair of bushing tubes, a plurality of metallic bands deposited on said bushings, means to secure selected bands to said cathode to carry said tubes in axial alignment with said cathode, another selected band being sealed to a grid cap mounted on one of said bushing tubes, a Wire assembly carried by said bushings, and means to couple conductors to said `grid cap and to said cathode.

MORRIS H. SHAMOS.

REFERENCES CITED The following references are of record in the le of this patent:

Korff: Electron and Nuclear Counters, 1946, D. Van Nostrand Co., Inc., New York, pp. 124 and 129. 

